Onyx is a powerful stack-based, multi-threaded, interpreted, general purpose programming language similar to PostScript. It can be embedded as an extension language similarly to ficl (Forth), guile (scheme), librep (lisp dialect), s-lang, Lua, and Tcl.

Onyx is perhaps the most advanced stack-based general purpose programming language in existence
It has the following distinguishing features:

Double-ended stacks are first class objects

Perl-compatible regular expressions.

Loadable module system.

Object-oriented programming (OOP) support similar to that of Objective-C